EasyWhist - description from Softdepia.com:
A interesting card game of Whist for two in which you
play against the computer. In this version you play against Grace, a lady who likes to win.
Originally called German Whist, for unknown reasons as it was created in Britain to a need for a Whist card game which could be played by two people rather than four.
The game comes with full instructions and is not difficult to play but makes you think a little bit.
EasyWhist is a "Free to try" program. You can download and try it for an evaluation period.